Eric Anderson stars as Rabbi Shlomo Carlebach in “Soul Doctor.” Based on previews, he may have to play taps soon. Photo: Carol Rosegg

There was a fun rumor going around that the opening-night party of “Soul Doctor,” a new musical about a singing rabbi, was so Orthodox, the men were separated from the women by a sheet.

I checked into this, hoping it was true. Alas, somebody was pulling my payos. The party was kosher (gluten-free kosher), but the men and women did mingle.

“There was no sheet,” says a source who attended the party. “Although now that I think about it, maybe there should have been. A sheet separating the show from the critics may have helped.”

Poor little “Soul Doctor.” I hate to beat up on such a defenseless little pisher, but it’s August and the big targets have yet to come into view.

So let’s make hay where we can.

“Soul Doctor” is based on the life of Shlomo Carlebach, a rabbi who wrote catchy songs in the 1960s that have become popular in synagogues. Carlebach died in 1994, but his daughter, Neshama Carlebach (a fine singer in her own right, by the way), is helping to keep his memory alive with “Soul Doctor.” She’s a big supporter of the show and even wanted to perform a concert on the stage of the Circle in the Square after the opening-night performance.

(She was dissuaded, since the show runs nearly three hours and her bonus concert would have meant nice, fat overtime checks for the stagehands.)

The producers of “Soul Doctor” are, I’m told, well-meaning but naive. They were blindsided by the negative reviews.

“Bizarre” and “bewildering,” wrote that noted Talmudic scholar Charles Isherwood.

“Muddy, bumbling and amateurish,” said New York magazine.

The Post’s Elisabeth Vincentelli, trying to be kind, called it “terminally earnest and relentlessly sunny.”

“Soul Doctor” was losing money in previews, and such notices would normally mean a closing notice this weekend.

But the producers, God love ’em, aren’t throwing in the prayer shawl just yet.

Production sources say they’re convinced the box office is going to pick up during the upcoming Jewish holidays.

It’s time to reopen my theater consulting booth in the Edison Hotel.

Gentlemen, in 100 years of Broadway history, not once has business boomed during the Jewish holidays.

Rosh Hashanah, the New Year, is a happy occasion, but that generally means family get-togethers ’round home and hearth, not trips to the theater.

And Yom Kippur is pretty serious business.

“Jews do not go to the theater around Yom Kippur,” says a veteran producer. “No one goes out on Yom Kippur. I’m secular, and I don’t go out.”

As a double whammy, the holidays fall the same week schools reopen, which traditionally causes the box office to dip.

“Maybe ‘Motown’ will make money that week, but not a show about a singing rabbi,” says the producer. “Who’s going to go? The practicing Jews won’t and the secular Jews aren’t going to say, ‘I don’t want to see a real rabbi in temple, but I want to see a singing rabbi on Broadway.’ ”

This producer concludes: “They are out of their minds.”

Time to start saying kaddish for “Soul Doctor.”

Don’t miss Sierra Boggess at 54 Below on Monday night. I caught her act earlier this week, and she was delightful. Best known as Ariel in “The Little Mermaid,” Boggess is an ingenue with a wicked sense of humor.

A highlight is her medley of Andrew Lloyd Webber songs, alternately sung by a pop star (modeled on Britney Spears) and a faux opera singer (modeled on Nicole Scherzinger).

The night I was there, the place was packed with teenage girls holding “Little Mermaid” programs. Boggess’ lovely version of “Part of Your World” was another highlight.

As an added bonus, you’ll get her father on guitar and her sister on cello.

Family fun all around!

Surely this press release for “How I Learned What I Learned” was written by a summer intern: “In this solo man show, Pulitzer Prize-winning playwright August Wilson shares stories about his first few jobs, a stint in jail, an early relationship, his first kiss, his foray into cinema and the friends he has had his entire life.”